1. Field of the Invention
This invention is directed to vehicle wheel alignment apparatus, and more particularly to the provision of an improved turning angle gauge for determining the magnitude and direction of wheel turn during the wheel alignment procedure.
2. Description of the Prior Art
The common turning angle gauge, of the character seen in HUNTER Bulletin, Form 900T-4 of October 1976, has a mechanical tracking mechanism in the base which includes a pointer which moves over a circular scale mounted in a position readily seen. A vehicle wheel alignment turn is performed, the gauge is caused to move in an X-Y direction to cause the scale and pointer to cooperate to display the degrees of turn scribed on the scale.
The problem with the mechanical turning angle gauges is that it requires an eyeball interpretation of the pointer position relative to the scale. There is also the problem of the fineness of the scale divisions, and how the scale is able to track the wheel turn and keep its desired alignment relative to the pointer.
It is known that U.S. Pat. No. 4,394,798 of July 26, 1983 is a turning gauge equipped with electronic pick-up. The problem with such a gauge is that a belt drive potentiometer is employed, the repeatability of the belt drive is not free of inaccuracies after a period of use, and there are a number of parts which can introduce errors.